Based on the overlay technique, the authors propose a novel algorithm for interactive walkthrough of complex polygonal virtual environments with global specular reflection effects in this paper. This algorithm integrates the global specular reflection preprocessing with visibility preprocessing. The problem of computing global specular reflection is then converted to that of determining the potential visible polygon set (PVS) through each mirror. A mirror-PVS-mapping G is constructed, associating the potential incidence beams with their respective PVS. At the stage of walkthrough, the proposed algorithm can synthesize the global specular reflection in real time by G mapping while calculating the other intensity components of the environment.